Some mobile electronic devices include a miniature patch antenna to enable them to communicate and provide a service, for example GPS navigation systems, WiFi, Bluetooth, and satellite mobile TV. It is commonplace today for users to use such devices inside motor vehicles. However the motor vehicle, being an essentially metallic enclosure may interfere with the reception of the device or weaken the signal that arrives at the device.
In order to overcome this problem the device's antenna may be provided in a separate unit that can be placed outside of the motor vehicle, for example on the roof of the motor vehicle. Typically a cable is either permanently or temporarily extended from the antenna into the interior of the motor vehicle so that it can be connected to the device.
One drawback of an external antenna is that it is susceptible to damage from external sources, for example from natural sources such as wind or rain, or from non-natural sources such as colliding with objects or vandalism.
U.S. Pat. No. 6,275,157 to Mays et al. describes an embedded RFID transponder in vehicle window glass. Mays et al. describes embedding an RFID device that is made up from a flexible circuit substrate with an antenna formed thereon and a transponder circuit disposed on the substrate and coupled to the antenna. The flexibility of the RFID transponder allows it to be placed between glass layers without the circuit breaking or the glass breaking during the manufacturing process.
Miniature patch antennas for UPS, WiFi, Bluetooth and other applications are generally rigid elements since they require the use of rigid materials with high dielectric constants to achieve compactness. As a result there is a problem to embed them between the layers of the glass of the windshield of a motor vehicle.